JPH09117093A - Electric motor power steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor power steering system in which the assembling work is facilitated by decreasing the number of components and the labor for assembling. SOLUTION: A control circuit 9 is disposed on the side of a motor in a motor housing with two brush holders 23 being secured integrally to an outer case 9b for holding a board 9a. Two brush holders 23 are constructed such that the center lines A, B of a brush inserting section pass through the central axis O of an armature while making an angle of 90 deg. (i.e., two brushes 22 are disposed at an interval of 90 deg. in the circumferential direction of a commutator 21). The motor wiring connecting the control circuit 9 and the brush 22 is realized by connecting an intermediate terminal 43 provided on the outer case 9b with each switching element 33 arranged on the board 9a by means of a bonding wire 44 and connecting a spring 45 contained in the brush holder 23 with the intermediate terminal 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus for assisting steering force of a vehicle.

[0002]

2. Description of the Related Art At present, an electric power steering apparatus (hereinafter abbreviated as EPS) for assisting a steering force of a steering by a rotation output of a motor is put into practical use. This E
The PS includes a motor that assists the steering force and a control device that controls a current flowing through the motor. However, since the motor and the control device are separately arranged, motor wiring that connects the motor and the control device is provided. Is becoming longer, and the number of wiring-related parts and the number of assembly steps are increasing. Therefore, the present applicant has applied for an EPS in which a motor and a control circuit are integrated and housed in a common motor housing (Japanese Patent Application No. 7-663).
No. 67). In this prior application, as shown in FIG. 8, the intermediate terminal 120 is insert-molded in the outer case 110 of the control circuit 100, and the bonding wire 1 from each switching element 130 in the control circuit 100 is inserted into the intermediate terminal 120.
The motor wiring is realized by connecting 40 and the pigtail 160 drawn out from the brush 150.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In S, there are the following problems. Since the brush 150 is arranged on the side opposite to the control circuit 100 with respect to the commutator 170, the pigtail 160 connecting the control circuit 100 and the brush 150 is inevitably long. Therefore, the pigtail 160 is attached to the clamper 18
Since it becomes necessary to fix it to the end frame 190 at 0 and the like, and the pigtail 160 needs to be insulation-coated with the sleeve 200, the number of parts and the number of assembling steps increase. Further, since the pigtail 160 from the clamper 180 to the control circuit 100 needs to have a margin for connecting to the intermediate terminal 120, the margin becomes loose after the connection. Therefore, when the loosened pigtail 160 contacts the armature, the motor wiring may be broken or short-circuited.

Because of the structure of the prior application, it is necessary to insert the armature into the end frame 190 after the pigtail 160 is connected to the intermediate terminal 120, and then to assemble the armature.
To prevent the brush 150 from springing out,
It is necessary to hold down against the biasing force of 20. In this case, the already assembled control circuit 100 interferes with the work, making it difficult to assemble the armature. The present invention has been made based on the above circumstances, and an object of the present invention is to provide an electric power steering device that can be easily assembled by reducing the number of parts and the number of assembling steps.

[0005]

According to the invention of claim 1, the brush is arranged on the control circuit side with respect to the commutator and the brush holder is integrated with the control circuit. Wiring can be shorter than before. As a result, it is not necessary to fix the motor wiring to the end frame (a part of the motor housing) or the like with the clamper, so that the number of parts can be reduced and the number of assembling steps can be reduced.

According to the invention of claim 2, the motor wiring is passed through the brush holder to connect the brush to the control circuit, so that the brush (brush holder) and the control circuit including the motor wiring are integrated. be able to.
Accordingly, the armature having the commutator can be assembled to the end frame in advance, and the brush can be brought into contact with the commutator at the same time when the control circuit is assembled later. As a result, the assembling can be performed easily and the slack of the motor wiring can be eliminated, so that there is no possibility of disconnection or short circuit of the motor wiring, and the reliability is improved.

According to the third aspect of the present invention, since the spring housed in the brush holder is used as a part of the motor wiring, the conventional pigtail is not required, the number of parts can be reduced, and the assembly relating to the wiring can be reduced. The number of steps can be reduced.

According to the fourth aspect of the invention, when the field pole of the motor has four poles, the two brushes are arranged at intervals of 90 degrees in the circumferential direction of the commutator. Can be made smaller. This makes it possible to evenly contact the brush with the outer peripheral surface of the commutator and prevent uneven wear of the brush.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an electric power steering system (EPS) of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view showing the internal structure of an EPS.
FIG. 2 is a configuration diagram showing a drive system of the EPS. EPS1
2, the output shaft 4 connected to the steering mechanism 3 via the speed reducer 2, the motor 5 for generating a rotation output, and the electromagnetic clutch 6 for transmitting the rotation output of the motor 5 to the output shaft 4. , A steering angle sensor 7 for detecting a steering angle (a rotation angle of the output shaft 4), a control circuit 9 for controlling a motor current according to a steering force of the steering wheel 8 and a vehicle speed, and the like.
Other components (motor 5, electromagnetic clutch 6, steering angle sensor 7, control circuit 9) other than the above are integrally housed in one motor housing 10 (see FIG. 1).

(Description of Motor Housing 10) As shown in FIG. 1, the motor housing 10 includes an end frame 11 to which the above-mentioned components are assembled, and an airtight assembly to the end frame 11 covering the components. And a motor case 12 that is used. The end frame 11 is made of a material having a high thermal conductivity (for example, aluminum), is brought into close contact with the end surface of the rack housing 13 that houses the steering mechanism 3, and is fastened with bolts 14 to tighten the rack housing 13.
It is fixed to. The motor case 12 is made of a magnetic material (for example, iron) and has one end side (upper end side in FIG. 1).
Has a closed bottomed tubular shape (cup shape), and is fixed to the end frame 11 by fastening a bolt 15 with a fixing portion 12a provided on the outer periphery of the opening peripheral edge portion. An outlet 17 for taking out the connector 16 of the control circuit 9 is formed between the motor case 12 and the end frame 11 on the open end side.

(Description of Motor 5) The motor 5 is provided on one end side of a field pole 18 (four poles in this embodiment) made of a permanent magnet, an armature 19 rotating on the inner circumference of the field pole 18, and an armature shaft 20. The commutator 21,
The armature 19 is composed of two brushes 22 (see FIG. 5) that are in sliding contact with the outer peripheral surface of the commutator 21 and a brush holder 23 that holds the brushes 22. (State shown in)
It is assembled in. The armature 19 is shown in FIG.
As shown in FIG. 1, one end side of the armature shaft 20, that is, the commutator 21 side is rotatably supported by the housing 25 of the electromagnetic clutch 6 via the bearing 24, and the other end side is provided on the bottom surface of the motor case 12 via the bearing 26. It is rotatably supported by the bearing 12c.

(Description of Electromagnetic Clutch 6) Electromagnetic Clutch 6
Is a coil 27 which is provided between the motor 5 and the output shaft 4 and whose energization is controlled via the control circuit 9.
A housing 25 which holds the housing 25 and is fixed to the end frame 11, and a rotor 2 which is connected to one end of the armature shaft 20 and rotates integrally with the armature shaft 20.
8, a disk-shaped rotating body 29 and the like which are connected to the output shaft 4 and rotate integrally with the output shaft 4. In the electromagnetic clutch 6, when the coil 27 is energized, the rotor 29 magnetized by the magnetic force of the coil 27 is attracted to the rotor 28, and the rotor 29 rotates integrally with the rotor 28. The rotational output of the rotor 28 and the rotating body 29.
Is transmitted to the output shaft 4. However, when the operation of the EPS 1 is abnormal, the coil 27 is stopped from being energized via the control circuit 9 so that the rotation output of the motor 5 is not transmitted to the output shaft 4, so that the armature shaft 20 and the output shaft 4 are separated from each other. The connected state is disconnected.

(Description of Steering Angle Sensor 7) Steering Angle Sensor 7
Is composed of a magnetic body 30 fixed to the outer peripheral surface of the rotating body 29 and a magnetic detecting means 31 (for example, a Hall IC) arranged on the outer periphery of the rotating body 29 so as to face the magnetic body 30.
The magnetic detection means 31 detects a change in magnetic flux generated by the rotation of the magnetic body 30 integrally with the magnetic body 9.

(Description of Control Circuit 9) In the control circuit 9, a connector 16 is provided integrally with an outer case 9b (made of resin) for holding a substrate 9a, and two brush holders 2 are provided.
3 are integrally fixed to the outer case 9b by welding or the like, and are arranged laterally of the motor 5 in the motor housing 10. The brush holder 23, as shown in FIG.
The center lines A and B of the brush insertion portion pass through the center axis O of the armature 19, and the angle formed by the two center lines A and B is 90.
It is configured to be a degree. That is, the two brushes 22 are fixed so as to be arranged at intervals of 90 degrees in the circumferential direction of the commutator 21. As shown in FIG. 1, the connector 16 is airtightly taken out from a take-out port 17 formed between the motor case 12 and the end frame 11 via a seal member 32.

As shown in FIG. 3, the control circuit 9 has an H
Four switching elements 33 forming a bridge circuit
(33a to 33d), an I / F circuit 36 that digitally converts the input signals from the torque sensor 34 that detects the steering torque and the vehicle speed sensor 35 that detects the vehicle speed, and this I / F circuit 3
A microcomputer (CPU) 37 that sets a motor current required for torque assist according to the steering force and the vehicle speed converted in 6, and an I / F circuit 38 that converts a digital signal output from the microcomputer 37 into an analog value. , A current detector 3 for detecting the current flowing through the motor 5
9. A current controller 40 that creates a duty signal for each switching element 33 based on the analog current command value converted by the I / F circuit 38 and the current value detected by the current detector 39. The generated duty signal and the direction to be torque assisted determined by the microcomputer 37 are input to drive each switching element 33, and the battery current accompanying the switching operation of each switching element 33 is smoothed. It is composed of a capacitor 42 and the like.

The motor wiring for connecting each switching element 33 of the control circuit 9 and the brush 22 of the motor 5 will be described below. The motor wiring connects the intermediate terminal 43 provided on the outer case 9b of the control circuit 9 and each switching element 33 mounted on the substrate 9a by a bonding wire 44 (see FIG. 4), and also connects to the brush holder 23. This is realized by connecting the other end of the spring 45 (conductor) that is housed and has one end connected to the brush 22 (see FIG. 5) to the intermediate terminal 43. However, the intermediate terminal 4
3 is insert-molded on the outer case 9b, for example,
One end is taken out from the wall surface of the outer case 9b facing the motor 5 into the brush holder 23 fixed to the outer case 9b (see FIG. 5), and the end of the spring 45 is welded to the intermediate terminal 43 thereof. Connected by.

Next, the operation of the EPS 1 of this embodiment will be described. When the driver steers the steering wheel 8, the steering force is detected by the torque sensor 34 and input to the control circuit 9. In the control circuit 9, the assisting torque is calculated according to the signal from the torque sensor 34 and the signal from the vehicle speed sensor 35, and the motor current for generating the torque is set. Then, a duty signal for driving each switching element 33 is created from the current command value that commands this motor current and the current flowing through the motor 5, and each switching element 33 is generated from this duty signal and the direction in which torque assist should be performed. Is turned on / off to vary the voltage from the battery 46 (see FIGS. 2 and 3) to the motor 5 to control the current flowing through the motor 5.

The torque generated by the motor current is transmitted to the output shaft 4 via the electromagnetic clutch 6, and further transmitted to the speed reducer 2 meshing with the output shaft 4 to generate the steering mechanism 3.
Torque assist. As a result, the steering force of the driver is reduced, the output of the torque sensor 34 decreases, and the steering operation ends. However, when the microcomputer 37 in the control circuit 9 diagnoses that the EPS 1 is operating abnormally, the coil 27 of the electromagnetic clutch 6 is de-energized and the connection state between the motor 5 and the steering mechanism 3 is disconnected. As a result, the driver can manually operate regardless of the state of the motor 5, and safety is ensured.

When the vehicle is turning, the tire 47 is used.
Since self-aligning torque (SAT: force to restore the steering wheel 8 to the neutral position) is generated in (see FIG. 2), when the steering wheel 8 is steered and then the steering wheel 8 is released, the neutral steering angle is always maintained by the SAT. The action of returning to the position acts on the steering wheel 8. But,
When the EPS 1 is mounted, the friction torque of the motor 5 (load torque when not assisting) is amplified by the speed reducer 2 and becomes larger than the SAT. Therefore, even if the steering wheel 8 is released, the steering wheel 8 is at the neutral steering angle position. Will not return to. Therefore, by detecting the steering angle with the steering angle sensor 7 and controlling the motor current based on the detected value, it is possible to perform restoration control to the neutral steering angle position when the steering wheel 8 is released.

(Characteristics and Effects of this Embodiment) In the EPS 1 of this embodiment, the brush holder 23 is fixed to and integrated with the outer case 9b of the control circuit 9 so that the motor wiring is passed through the inside of the brush holder 23. Can be connected. As a result, the motor wiring is shortened and it is not necessary to fix the motor wiring to the end frame 11 with a clamper or the like, so that the number of parts can be reduced and the number of assembling steps can be reduced. Further, since the brush 22 (brush holder 23) to the control circuit 9 including the motor wiring can be integrated, by assembling the control circuit 9 after assembling the armature 19 to the end frame 11, At the same time, the contact between the brush 22 and the commutator 21 can be completed. As a result, the assembling can be easily performed and the slack of the motor wiring can be eliminated, so that there is no risk of disconnection or short circuit of the motor wiring, and reliability is improved. Furthermore, by using the spring 45 housed in the brush holder 23 as a part of the motor wiring,
Since the conventional pigtail is not required, the number of parts can be reduced and the number of wiring assembling steps can be reduced.

(Second Embodiment) FIG. 6 is a sectional view showing the internal structure of the EPS 1 according to the second embodiment. In this embodiment,
It shows an example of using a pigtail 48 as the motor wiring. When the brush 22 connects the intermediate terminal 43 with the spring 45 as shown in the first embodiment, when the current capacity becomes large (about 20 A), the wire diameter of the spring 45 also needs to be thickened.
The contact force between 2 and the commutator 21 increases, and the requirement for the motor 5 is not satisfied. Therefore, as shown in FIG. 6, the brush holder 23 is fixed at a location different from the intermediate terminal 43, and one end of the pigtail 48 connected to the brush 22 is connected to the intermediate terminal 43 (for example, by welding) to connect the motor wiring. May be realized. The pigtail 48 can be connected to the brush 22 at a place where it does not come into contact with the commutator 21, and can be taken out of the brush holder 23 through a slit (not shown) formed in the brush holder 23 in advance.

In this case, the brush holder 23 has the control circuit 9
Since it is integrated with the outer case 9b, it is not necessary to allow the pigtail 48 to have a margin at the time of assembling, so that its length can be set to a necessary minimum. Therefore, there is no risk of disconnection or short circuit of the motor wiring due to the provision of the pigtail 48, and reliability is not impaired. The brush holder 23 is the same as in the first embodiment.
Is fixed to the takeout part of the intermediate terminal 43, and the pigtail 4
It is also possible to pass 8 through the brush holder 23 and connect it to the intermediate terminal 43. However, it is necessary to insulate the spring 45 and the intermediate terminal 43.

(Third Embodiment) FIG. 7 is a plan view showing how the brush holder 23 is attached. The brush holder 23 fixed to the outer case 9b of the control circuit 9 needs strength enough to properly hold the brush 22 against the contact force between the commutator 21 and the brush 22. That is, when the brush holder 23 bends due to the contact force between the brush 22 and the commutator 21, the brush 22 is unevenly worn or the brush 2
2 causes the deterioration of the motor characteristics due to the displacement. Therefore, usually, the strength of the brush holder 23 is set to be sufficiently larger than the contact force between the brush 22 and the commutator 21, but as shown in FIG. 7, the reinforcing material 49 is provided between the two brush holders 23. By passing and fixing the brush holder 23, the angle (90 degrees in this embodiment) formed between the two brush holders 23 can be kept constant even if the strength of the brush holder 23 is not sufficient.

(Modification) The brush 22 is an armature 19
When the heat is transmitted to the control circuit 9, the brush holder 23 is made of metal, and the end frame 1 is pre-insulated (for example, anodized).
This can be dealt with by allowing the brush holder 23 and the brush holder 23 to come into close contact with each other with an adhesive or the like having good thermal conductivity and allowing the heat to escape from the brush holder 23 to the end frame 11.

[Brief description of the drawings]

FIG. 1 is an overall sectional view showing an internal structure of an EPS (first embodiment).

FIG. 2 is a configuration diagram showing a drive system of an EPS.

FIG. 3 is a block diagram showing an internal configuration of a control circuit.

FIG. 4 is a perspective view showing a connection method in a control circuit.

FIG. 5 is a schematic diagram showing a method of connecting a brush and a control circuit.

FIG. 6 is an overall sectional view showing the internal structure of the EPS (second embodiment).

FIG. 7 is a plan view showing a mounting state of a brush holder (third embodiment).

FIG. 8 is a plan view showing a motor wiring connection method adopted in the EPS of the prior application.

[Explanation of symbols]

 1 EPS (Electric Power Steering Device) 3 Steering Mechanism 5 Motor 9 Control Circuit 10 Motor Housing 11 End Frame (Motor Housing) 12 Motor Case (Motor Housing) 18 Field Pole 19 Armature 21 Commutator 22 Brush 23 Brush Holder 45 Spring

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yuji Hashiba 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor Kenji Takeuchi 1-1-chome, Showa town, Kariya city, Aichi prefecture Sozo Co., Ltd.

Claims (4)

[Claims] 1. An electric motor which includes a motor for rotating an armature when a current flows through a commutator through a brush and a control circuit for controlling a current flowing through the motor, and which assists a steering mechanism of a vehicle with a torque by a rotational output of the motor. In a power steering apparatus, a motor housing that integrally houses the motor and the control circuit is provided, the control circuit is disposed laterally of the motor in the motor housing, and the brush is provided in the commutator. On the other hand, the electric power steering device is characterized in that two brush holders are arranged on the control circuit side and hold the respective brushes, which are integrated with the control circuit. 2. The electric motor according to claim 1, wherein a motor wiring connecting the brush and the control circuit is connected from the brush to the control circuit through the brush holder. Power steering device. 3. A spring housed in the brush holder to press the brush against the outer peripheral surface of the commutator, and the spring constitutes a part of the motor wiring. The electric power steering device described in 1. 4. The motor according to claim 1, wherein the field poles arranged on the outer periphery of the armature have four poles, and the two brushes are arranged at intervals of 90 degrees in the circumferential direction of the commutator. The electric power steering device according to any one of claims 1 to 3.